The objective of the proposed project is to define the molecular mechanisms by which the responsiveness of ovarian follicles and corpora lutea (CL) to gonado-hormones is regulated. The hormonal responsiveness of a tissue is as important in determining the magnitude of the response elicited as is the serum concentration of the hormone. Tissue responsiveness encompasses at least the hormone-receptor adenylyl cyclase and protein kinase enzyme systems. Emphasis is placed upon the regulation by luteinizing hormone, prolactin, estrogen, and the catecholamines of the presence, activity, and responsiveness of the receptor-coupled adenylyl cyclase and protein kinase enzyme systems in ovarian follicles and CL. The effect of various in vivo manipulations during different states of reproduction on the hormonal milieu surrounding ovarian tissues will be determined both by subsequent in vitro characterizations of the ovarian adenylyl cyclase and protein kinase enzyme systems and, when appropriate, by the steroidogenic response of these tissues. It is through such studies on the interregulation by all of the gonado-hormones of these key enzyme systems that we can understand the molecular mechanisms of action, and therefore the function, of the gonado-hormones in ovarian follicles and CL.